Maybe, as the DOM becomes more loaded with more abstractions, people will start re-implementing abstractions the DOM already provides; just the subset of abstractions they want. Whether their implementation can beat the native code of the DOM, and the bandwidth concerns of reshipping the same logic is another story.
You can have accessibility without the DOM, and really the DOM is not such a great way to do this anyway. Just do things like write explicit audio-only interfaces.
That's a pretty narrow view of "accessibility". For example, you just assumed that your user can't see (or can't see very well?) but can hear.
Users who are deaf and blind? Out of luck. Users who are deaf and not blind but need your thing zoomed to a larger size? Maybe out of luck maybe not (depends on whether the WebGL app detects browser zoom and actively works to defeat it like some do). Users who are deaf and not particularly blind but happen to not be able to tell apart the colors you chose to use in your WebGL? Also out of luck.
What the DOM gives you is a semantic representation that the user can then have their user agent present to them in a way that works best for them. Reproducing that on top of WebGL or canvas really is quite a bit of effort if you really want to target all users and not just a favored few groups.
I assumed we were talking about vision impairment, because that's what the comment I replied to mentioned. Of course you can implement whatever else you want as well.
I question this "semantic DOM" idea: the trend has been towards filling the DOM with tons of crap in order to make applications, not documents. Do accessibility agents even work well on JavaScript heavy sites today?
Accessibility can and will be had without the DOM; while it is a concern, it shouldn't prevent things like WebGL + asm.js apps on the web.
My point is that visual impairment is not mutually exclusive with other impairment, even though people often assume it is, consciously or not. This is an extremely common failure mode, not just in this discussion.
And while of course you _can_ implement whatever else you want, in practice somehow almost no one ever does. Doubly so for the cases they don't think about or demographics they decide are too small to bother with.
How well accessibility agents work on JS heavy sites today really depends on the site. At one end of the spectrum, there are JS heavy sites that still use built-in form controls instead of inventing their own, have their text be text, and have their content in a reasonable order in the DOM tree. At the other end there are the people who are presenting their text as images (including canvas and webgl), building their own <select> equivalents, absolutely positioning things all over the place, etc. Those work a lot worse.
You are of course right that accessibility can be had without the DOM, but "webgl" is not going to be it either. Accessibility for desktop apps typically comes from using OS-framework provided controls that have accessibility built in as an OS service; desktop apps that work in low-level GL calls typically end up just as not-accessible as your typical webgl page is today. So whatever you want use instead of the DOM for accessibility purposes really will need to contain more high-level human-understandable information than which pixels are which colors or what the audio waveform is. At least until we develop good enough AI that it can translate between modalities on the fly.
Speaking about AI, is it really that hard to do the OCR'ing of the images?
I'm no expert, but I was under the impression hat this was a solved problem.
E.g. Mac OS X uses OpenGL to render GUI, I guess I should have made myself more clear.
> WebGL and canvas are in no way replacements for the DOM.
That's kind of debatable. If you have access to a fast graphics layer from the browser, you can build a DOM replacement of sorts. I think that famo.us works kind of like that.
It's true that OS X uses OpenGL for GUI compositing, but that's only the lowest level. Above, there's a very important piece of the GUI stack called Core Animation which provides layer compositing.
Core Animation is used by both the native GUI as well as the browser DOM. When you use layer-backed compositing on a web page (e.g. CSS 3D transforms), WebKit implements it with a Core Animation layer. So DOM-based rendering enjoys the same benefits of GPU-accelerated compositing as native apps -- although obviously with rather different semantics since HTML+CSS doesn't map directly to Core Animation.
If you implement your own GUI framework on top of WebGL or Canvas, you're not getting Core Animation compositing for free, so you need to replicate that functionality in your custom framework. (This applies equally to native apps: a WebGL app is equivalent to a Cocoa app that renders everything into a single OpenGL view, and a HTML Canvas app is equivalent to using a single CoreGraphics view.)
I don't think the WebGL/Canvas route makes sense for most apps other than games and highly visual 3D apps. You'll just spend a huge amount of time building your own implementations of all high-level functionality that is already provided by the OS and/or the browser: layer compositing, text layout, view autosizing, and so on. If you're doing standard GUIs, why go to all that trouble?
> You'll just spend a huge amount of time building your own implementations of all high-level functionality that is already provided by the OS and/or the browser
Not only that, but you can't make a 100% guarantee that your implementation will look and work exactly the same as the native one on the underlying OS. For instance, I can re-create all the native Windows UI controls and re-implement all their behavior in exactly the same way, but what if the user has a custom theme installed? Everything breaks. (WPF has a similar problem.)
I agree that it would be a lot of effort to pull off since you'd have to duplicate a lot of the standard OS features in the browser but if eventually the DOM becomes an even bigger bottleneck, it might be a viable solution.
To some degree, yes. You just have to be able to re-use system UI controls like fields. So you wouldn't be able to just use WebGL/canvas/whatever in place of the DOM, you'd need to come up with a new API.
Until the web becomes the dominant operating system, I don't think that's reasonable because you'd have to implement an entire UI kit (with all UI components, behaviors, animations, etc) but can't guarantee that it will behave at all like the underlying OS. There's only so much you can re-create in the browser.
Perhaps it's to make it backward compatible, so that, for example, the traditional DOM is implemented as a Javascript library that parses HTML and renders it onto a WebGL surface?
Graphically intensive apps do it for performance. But the tradeoff is you lose all the native UI controls that the OS gives you--form fields, text selection, animation, etc. So I don't think replacing the DOM with OpenGL or similar is a good solution for general-purpose apps.
Yes, they already are. That framework is called the DOM. People keep complaining about it and trying to come up with replacement frameworks that end up slower and less capable...
The DOM definitely has its problems, mind you. Investing some time in designing a proper replacement for it is worth it, as long as people understand going in that the project might well fail.
>Yes, they already are. That framework is called the DOM. People keep complaining about it and trying to come up with replacement frameworks that end up slower and less capable...
The ones I've seen are actually faster -- Flipboard for one gets to 60fps scrolling on mobile, IIRC. And of course all WebGL based interfaces on native mobile apps that re-implement parts of Cocoa Touch et al, are not that shabby either.
Sure, it doesn't have as much accesibility, but that's something that can be fixed in the future (and of course people needing more accessibility can always use more conservative alternatives).
None have tried to replace all of it that I know of.
People have tried to replace things like text editing (with canvas-based editors), CSS layout of the DOM (with various JS solutions involving absolute positioning), native MathML support (MathJax; this one has of necessity done better than most, because of so many browsers not having native MathML support). There are a bunch of things out there that attempt to replace or augment the built-in form controls, with varying degrees of success.
That's my point. Currently, you cannot really replace the DOM since that's kind of the extent of the exposed APIs.
None of the projects that you mention are really relevant to the discussion. I agree that they didn't change shit but it's precisely because they are still built on the DOM and cannot really go below that in the abstraction layer.
>I agree that they didn't change shit but it's precisely because they are still built on the DOM and cannot really go below that in the abstraction layer.
There exist UIs done in Canvas and WebGL that are arguably below the DOM in the "abstraction layer" and don't need to use much more DOM nodes besides opening a canvas/gl panel...
(Most full screen 2G/3G web games fall into this, for starters, and those are in the tens of thousands. But there are also lotsa apps).
Flipboard's from the recent story? The resulting site breaks accessibility and the layout obviously has less capability, but it's certainly not slower.
